1. Field of the Invention
The invention relates to an internal combustion engine system, a method of controlling the internal combustion engine system, and a vehicle.
2. Description of the Related Art
Japanese Patent Application Publication No. 2006-161575 (JP-A-2006-161575) describes an internal combustion engine system according to a related art. The internal combustion engine system includes a throttle valve, an exhaust gas recirculation passage, and a catalyst. The throttle valve is driven by a throttle motor. The exhaust gas recirculation passage provides fluid communication between an intake passage and an exhaust passage. An EGR valve is provided in the exhaust gas recirculation passage. The catalyst is installed in the exhaust passage for purifying exhaust gas. Exhaust gas is recirculated to the intake passage during execution of fuel cut at the time of deceleration. In this system, when depression of an accelerator pedal is detected during fuel cut, the flow rate of exhaust gas recirculated to the intake passage during a period from when the depression of the accelerator pedal is detected to when the opening degree of the throttle valve is actually varied is attenuated, thus reducing a decrease in acceleration at the time of forcible return from fuel cut.
Generally, in order to suppress a decrease in output torque at the time of return from fuel cut, the above described internal combustion engine system executes control for starting fuel injection at a fuel injection flow rate that is obtained by increasing a reference fuel injection flow rate by a correction flow rate. The reference fuel injection flow rate is set so as to attain a stoichiometric air-fuel ratio with respect to an intake air flow rate. The intake air flow rate is detected by a sensor, such as an air flow meter, installed in an intake pipe. However, when EGR is being performed, the intake air flow rate detected by the sensor differs from the air flow rate actually introduced into a combustion chamber of an internal combustion engine. Therefore, it is desirable to further appropriately increase the reference fuel injection flow rate by a correction flow rate to resume fuel injection.